Apparatus for making magnesium die castings



L. H. MORIN 3,452,805

APPARATUS FOR MAKING MAGNESIUM DIE CASTINGS July 1, 1969 Filed Dec. 22, 1 965 4 2 5 Z W G y f 3 @Om W I I 1\ 2 u. 5 w o w i N m M0 M m. H 5 0 0 HTTORNEY United States Patent US. Cl. 164-154 6 Claims ABSTRACT OF THE DISCLOSURE A combination storage pot for molten metal and means removably attached to the top thereof to pressure inject said metal through a nozzle with a die.

This invention relates to the formation of magnesium die castings, wherein what I term a gooseneck holding pot is employed, in the chamber and gooseneck of which magnesium is stored preparatory for use in the formation of die castings and, wherein, means is employed to maintain the magnesium in a molten state under temperature control, not only at the chamber portion of the pot but also at the nozzle end of the gooseneck.

More particularly, the invention deals with apparatus, wherein a cover unit is employed and sealed upon the top of the pot, the cover unit including means for pressure discharge of the molten magnesium in formation of cast end products, which means can comprise the intermittent application of hydrostatic pressure by the use of an inert gas and then exhausting the gas upon completion of the casting of an end product.

Still more particularly, the invention deals with a method and apparatus, wherein the gooseneck holding pot includes a supporting extension facilitating attachment and detachment of the magnesium holding and ejector assemblage in a machine, as well as providing pivotal support of said assemblage in the machine.

The novel features of the invention will be best understood from the following description, when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed and, in which, the separate parts are designated by suitable reference characters in each of the views and, in which:

FIG. 1 is a schematic sectional view illustrating one adaptation of my invention, parts of the construction being shown in elevation and parts broken away; and

FIG. 2 is a schematic view, generally similar to FIG. 1, on a reduced scale showing another adaptation of forming magnesium die castings.

The making of magnesium die castings has always been a problem, due principally to the fact that magnesium oxidizes quite readily when exposed to the atmosphere and also burns readily.

Magnesium has been successfuly die cast in the socalled cold chamber machines, but this is a slow process. It has also been die cast in hot chamber machines, but quite a complicated machine and arrangement are necessary because of the fact that the open pot is exposed to the atmosphere and the gooseneck is exposed to the atmosphere, all of which, in turn, has to be housed in some manner and finally shrouded with an inert gas, such as nitrogen, which complicates the operation and the machine considerably. It makes it quite diflicult to mechanically service such a machine arrangement.

Supplying the machine with fresh metal represents a problem, because, somewhere, an opening has to be created for introducing the metal which, again, must be sealed oif, at least sealed oif with an inert gas layer.

My apparatus can be utilized in the formation of all types and kinds of magnesium die castings and it is par 3,452,805 Patented July 1, 1969 ticularly adaptable for use in making small magnesium die castings, for which there is a great demand.

Considering FIG. 1 of the drawing, at 10 is schematically illustrated what can be termed a magnesium holding and ejector assemblage This assemblage comprises what I term a gooseneck holding pot 11, including a gooseneck extension 12, having a bore 13 extending into the lower portion of the chamber 14, as clearly noted. At 15 is shown a nozzle securely seated in a tapered seat 16 at the discharge end of the extension 12. At 17 is shown, in part, a pressure flame burner for maintaining the nozzle 15 at the proper temperature at all times.

A suitable die is illustrated, in part, at 18, the die including a gate 19 opening into a cavity 20 for forming a suitable cast end product illustrated, in part, at 21. Suitably fitted in the chambered portion of 11 is a pyrometer 22, preferably having a quick disconnectable electrical fitting, as diagrammatically seen at 23. Below the chambered portion of 11 is shown, in part, a burner 24 for maintaining the magnesium 25 in the chamber 14 at the proper temperature, as will be apparent to those skilled in the art. While a gas-type of flame has been diagrammatically illustrated at 26, it will be apparent that other types of heating medium can be employed. The pyrometer with the use of suitable temperature control instruments, well-known in the art, will turn the heat of the burner 24 off and on, as required, in maintaining the desired temperature of the magnesium 25. This will also control the flame burner, as at 17. In the accompanying drawing, the magnesium has been illustrated in stippling to clearly illustrate a differential between it and the crosssectioning of the metal parts and, further, in illustrating its molten state.

It will be noted that the gooseneck holding pot 11 includes an integral upwardly directed extension 27 extending upwardly, primarily from the gooseneck extension 12, this extension 27 terminating at its upper end in a hook portion 28, beneath which is another hook portion 29. The extension includes a reinforcing rib 27'.

At 30 is shown the gooseneck swiveling shaft of a die casting machine, around which the entire assemblage 10 pivots. Swiveling around the shaft 30 is the bearing 31 of an extension arm 32 having, at its end, a stud 33 which will rest in position in the hook 29, as diagrammatically shown. Thus, when the assemblage 10 is in position, the nozzle 15 will be supported in proper registering position with the gate 19 of the die 18 in the manner diagrammatically illustrated. The arm 32, to-

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gether with its stud 33, serves to swing the assemblage 10 in movement of the nozzle 15 out of engagement with the die 18, as later described.

Extending from the bearing 31 is a lever 34. In the clevis end 35 of the lever is mounted a cam roller 36. At 37 I have shown the cam shaft of the casting machine which is suitably rotated, for example in the direction of the arrow 38, in the manner known in the art, so as to rotate the shaft at the prescribed speed in formation of successive die cast end products, as at 21.

Mounted on the shaft 37 is a cam 39 which operatively engages the roller 36 to swing the assemblage 10 in the direction of the arrow 40, so that the contact between the nozzle 15 and the die 18 will be intermittently broken. The cam 39 is so timed that, when the contact is again established with the die 18, an injection or shot then takes place.

Mounted upon the gooseneck holding pot 11 is a cover unit 41 supported upon a sealing gasket 42 at the upper end of the chambered portion of 11, as diagrammatically seen. The unit 41 is retained in pressure engagement by means of a plurality of tie bolts, one only of which is seen at 43, each bolt pivoting on a pin 44 fitting in a clevis 45 which is integral with 11, as diagrammatically seen. At least three of the bolts 43 will be employed to securely retain the unit 41 in engagement with 11.

Another cam 46 is mounted on the cam shaft 37 and a connecting link 47 is moved radially on the shaft 37, the link having rollers 48 and 49 at end portions thereof operatively engaging the cam 46. The end portion of the link 47 having roller 49 includes an extension supporting a pin 50 forming a pivotal support for a T-shaped lever 51 for actuating valves in what might be called a valve head extension 41' on the cover unit 41. In the illustration in FIG. 1, it will appear that the raised portion 52 has engaged the roller 49 in moving the lever 51 in the direction of the arrow 53, the lever swinging on a pivotal support 54 on 41. In this action, the lever 54 depresses a valve stem 55 in movement of the valve head 55' into open position, allowing compressed inert gas such, for example, as nitrogen, to enter through a suitable flexible pipe, not shown, but indicated by the arrow 56. A bayonet-type connection for the flexible pipe is illustrated at 57, this type of connection being employed to provide a quick uncoupling feature, similar to the quick uncoupling, as provided at 23, as and when the assemblage is removed, as later described.

Upon opening the valve 55', the inert gas is discharged through the passage 58 into chamber 14 and a top of the molten magnesium 25. This operation creates the so-called shot or injection of the magnesium into the cavity in forming the cast product 21. It should here be kept in mind that the nozzle has, by proper timing, contacted the die prior to this shot.

In the cycle of operation, the cam portion 52 traveling in the direction of the arrow 38 then proceeds to actuate the roller 48 to swing the lever 51 into position, depressing the valve stem '59, thus moving the valve head 59 into open position, allowing the inert gas to be discharged from the upper end of chamber 14 through the passage 60 and port 61. It will be understood, at this time, that the valve head 55 has been moved into closed position by the spring, diagrammatically shown on the stem 55, a similar spring being arranged upon the stem 59 for normally maintaining the head 59' in seated position.

In the above described operations, it will be apparent that the lever 34 is constantly kept depressed in the direction of the arrow 62 by any Suitable spring-loaded medium, not shown, to constantly maintain the nozzle 15 in engagement with the die 18 during the shot period. The cam 39 engaging the roller 36 moves the nozzle into a position disengaging the die 18, which action is against the force indicated by the arrow 62. Descriptively speaking, the arrow 62 represents a schematic showing of means for accomplishing the desired end result. In the same manner, the arrow 56 again represents a means for admission of inert gas. This type of showing has been employed to simplify the overall illustration as, admitted- 1y, those skilled in the art will fully understand the type of means which can be employed in the two incidents defined.

At this time, it is pointed out that, in the initial filling of the chamber 14 of the gooseneck holding pot, the magnesium should be at a level designated by the dot-dash line 63, in other words, to be well below the discharge of the nozzle 15. This prevents any chance of spilling of the metal through the nozzle when the assemblage is in the inert position, in other words, when all pressure has been exhausted to atmosphere and when moving the assemblage to the operating position.

It will be observed that, when 23 and 56 have been uncoupled and the cover unit 41 detached from the assemblage 10 by movement of the bolts 43 into inoperative position and the unit 41 moved to a position over the shaft 37, the assemblage 10 is easily removable by displacement of the hooks 28 and 29 from and 33, respectively. The assemblage 10 is now moved to a place remote from the machine, where the unit is re-charged with molten magnesium. Here, it will be apparent that each machine may have two or three such assemblages so that, while some are being charged with molten magnesium, another is in the machine making castings. Upon installing each of the assemblages in the machine, the molten magnesium is kept under heat and temperature control to be ready for prompt use. In this way, oxidization of the metal is obviated.

In the above described operation, it will be apparent that both of the valve heads 55, 59' will be actuated in each cycle of operation of the machine and, in each cycle, the assemblage 10 is swung on its pivot 30 by action of the cam 39 to remove the nozzle 15 from the die 18 on completion of the shot or injection of the molten metal to form the cast product 21. The extent of use of each assemblage 10 in the machine will depend largely upon the size of the end product being formed as compared to the volume of storage of the molten magnesium 25 in the chamber 14 of the gooseneck holding pot.

Turning now to the schematic showing in FIG. 2 of the drawing, here the various components are generally the same, with the exception of the type of cover unit employed and this structure is briefly described as follows.

10 represents an assemblage, generally similar to the assemblage 10, in other words, employing the gooseneck holding pot 11, extending a gooseneck extension 12' having a bore 13 extending into the lower portion of the chamber 14, as clearly noted. 15' is the nozzle. 17' is the nozzle heating means. 18 is the die. On 11' is an extension 27", similar to 27, supported on a shaft 30 and stud 33', similar to the showing in FIG. 1. At 34 is shown a lever, similar to the lever 34, supporting at its end a roller 36 operatively engaging a cam 39' on a shaft 37' for movement of the assemblage 10, similar to the operation as described in connection with FIG. 1 of the draw ing. At 62' is shown the means or force for normally maintaining the nozzle 15' in engagement with the die 18'.

At 64 is shown a modified form of cover unit which includes clamp bolts 43', similar to 43, but 64 differs from 41 in having an upwardly extending sleeve or tubular portion 65, in which is fitted a displacement piston 66, which normally rests upon the molten magnesium arranged in the chamber 14', as diagrammatically illustrated. It will be apparent that the gasket seal 42 is also employed. This displacement piston 66 is preferably made hollow, as indicated by the chamber 67 therein, thus the piston 66 acts as a float upon the magnesium 25. With this structure, I also employ a pressure applying member or actuator 68, which normally rests upon the top of the piston 66. However, when 68 is actuated downwardly by suitable means, not shown, the displacement piston 66 will force the molten magnesium out through the nozzle 12' into the die 18 in forming a cast product, similar to the diagrammatic showing in FIG. 1. At this time, it is pointed out that the member or actuator 68 can be operated by mechanical or hydraulic means, or can be air actuated, but at no time is air introduced into the chamber 14' to contact the magnesium 25'.

The cycle of operation of the showing in FIG. 2 of the drawing will be generally the same as that shown in FIG. 1, modified only to the extent of the mechanism employed and it will, of course, be apparent that, with the assemblage 10', the heating medium for the gooseneck holding pot 11' will be of the type and kind illustrated in FIG. 1 and modified to the extent set forth, the magnesium 25' being always kept at the desired temperature under the thermostatic control, as partially illustrated at 22. in FIG. 2.

For purposes of description, the gas exhausted from the chamber may be regarded as spent gases and, further, the expression mechanism can be said to define the gooseneck pot, including the cover unit and the parts associated therewith.

In connection with the pre-charging of the assemblage, as noted above, in many instances, it would be desirable primarily from the standpoint of preventing oxidation, to remove the assemblages including the cover units from the casting machine in their assembled state and delivering the same to the re-charging station, and in delivery of the combination including the attached cover units from the charging station to the machine. From this standpoint, the quick detachable mounting in the casting machine is advantageous. With the structure shown in FIG. 1, all that is necessary in detaching the complete assemblage would be to remove the pin 50 to disengage the T-shaped lever 51, which action will automatically move both valve heads 55 and 59' into operating or seated position and upon disconnecting the flexible pipe, designated by the arrow 56, from the bayonet-type connection 57, and detaching the electrical fitting 23, the complete assemblage can be removed and a new assemblage quickly installed, as will be apparent. With the structure shown in FIG. 2 of the drawing, it will be apparent that the piston 66 will be positioned to provide suflicient clearance for detachment of the assemblage.

Having fully described my invention, What I claim as new and desire to secure by Letters Patent is:

1. In a die casting machine, a mechanism for forming magnesium die castings in a die of the machine, said mechanism comprising a readily replaceable magnesium holder and ejector assemblage consisting of a gooseneck pot, the pot having a magnesium receiving chamber, including a discharge through the gooseneck of the pot, a nozzle at the end of said gooseneck, means for heating the pot, means for heating said nozzle, means in the pot controlling said first and second named means in maintaining predetermined temperature of the magnesium in said gooseneck pot, means on the assemblage engaging a shaft of the casting machine for detachable pivotal support of said assemblage in the machine to register a discharge of said nozzle with a gate opening into a cavity of said die, means on said shaft operatively engaging said last named means for support of the nozzle in spaced relation with the die after the shot of magnesium into the die cavity to form a cast product, means actuating said fifth named means for swinging the assemblage on said shaft in withdrawing the nozzle from said die on completion of the shot, a cover unit for the pot, means including clamp bolts for pressure sealing the cover on the pot, and said unit having means for pressure discharge of molten magnesium into the die cavity.

2. A mechanism as defined in claim 1, wherein said sixth named means includes a cam on a cam shaft of the casting machine.

3. A mechanism as defined in claim 2, wherein said eighth named means includes a pair of spring seated valves controlling intake and discharge of an inert gas with respect to the chamber of the pot, and means actuated by a cam on said cam shaft for intermittently actuating said pair of valves.

4. A mechanism as defined in claim 1, wherein said last named means comprises a hollow displacement piston floating on the molten magnesium in said chamber, and means operatively engaging said piston for pressure feeding of the piston into said chamber in the casting shot.

5. In a die-casting machine, a mechanism for forming magnesium die castings, a gooseneck holding pot as semblage comprising a pot portion including a chamber for storage of molten magnesium, a gooseneck portion integral with the pot portion, said gooseneck portion having a bore opening into the lower end of said chamber and out through the upper end of the gooseneck portion, a discharge nozzle at the upper end of said gooseneck portion, said assemblage including an upwardly directed supporting extension the top of which is above said assemblage, said extension having near the upper end thereof hook means adapted for ready pivotal and detachable engagement with a support in a die casting machine, and means spaced with respect to said first named means adapted to be engaged by means in a die casting machine for intermittently swinging said assemblage on its pivotal support.

6. An assemblage as defined in claim 5, wherein means is provided on the upper end of the pot portion for detachably coupling a cover unit therewith to seal the chamber of said pot portion.

References Cited UNITED STATES PATENTS 2,609,575 9/1952 Morin 164-318 3,179,295 4/1965 Morin 164-310 2,448,903 9/1948 Miller 164309 FOREIGN PATENTS 533,272 2/ 1941 Great Britain.

5 J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

US. Cl. X.R. 164306, 312 

